Ideas symbolise the essence of an individual’s creativity and are intimately associated with creative workers’ identities that hitherto felt shielded from previous technological change. That was until generative AI emerged with its broad capabilities that imitate the expertise and skills of creative occupations. Creativity and generative AI are increasingly the focus of scholarly enquiry, yet the human effect of equivocal technological transformation on creative workers has received little attention. Drawing on in-depth interviews with fifty-six design experts, we examine the impact of designers’ inherent idea generation as generative AI became increasingly accessible and capable—making three distinct contributions. First, we establish idea generation as an intrinsic component of designers’ occupational identity. Next, we observe generative AI fracturing designers’ locus of idea generation—shifting it from human- to machine-agent—destabilising the balance of power and relationship between designer and their ideas. Last, we discover a perpetual transformation with generative AI’s capabilities constantly enhancing and accessibility increasing—a phenomenon we describe as generative disruption. Designers’ responses are unpredictable—loaded with tension and contradiction—with existing literature not accounting for this phenomenon we notionally call epistemic flux. These findings also illuminate fertile foundations for future enquiry and theorising.